The
guinea worm, Dracunculus medinensis, has been known from very
ancient times. This nematode causes dracunculiasis, a very debilitating,
easily preventable infection transmitted by drinking contaminated water.
It is fortunately now on the verge of eradication in its last remaining
stronghold among the rural poor of sub-Saharan Africa.

The Ebers papyrus, dating from 1550 B.C., described the disease and
its primitive treatment, still used in most endemic areas today. A calcified
guinea worm was discovered in the abdominal cavity of an adolescent
Egyptian mummy dating to the beginning of the first millenium B.C. Egyptian
mythology pertaining to the Serpent of Isis has been postulated as relating
to dracunculiasis. The "plague of the fiery serpents" which decimated
the Hebrews during the Exodus from Egypt, as described in the Book of
Numbers, is undoubtedly a reference to guinea worm infection.

The
early Greek and Roman physicians associated the disease with certain
watering holes and wells. Agatharchides in 140 B.C. and other historians,
including Plutarch and Galen, also referred to the disease. Arab and
Persian writers of the Middle Ages described the disease and a Persian
doctor of the 10th century identified a worm as its cause. In the 11th
century, Avicenna gave an exact description of dracunculiasis, including
its treatment and complications if the worm breaks while being extracted,
thus confirming that the disease was prevalent in ancient Persia. In
1598, Pigafetta, in writing of his travels to the Congo, made drawings
of the female worm and the clinical signs it produced. In 1758, Linnaeus
described the adult worm and, in 1871, Fedchenko elucidated its parasitic
cycle.

For centuries, D. medinensis was associated with an unusually
high incidence in the city of Medina, from which it derives part of
its name. A similar high incidence in the country of Guinea in West
Africa gave the worm its other common name. The slaves who were transported
from the Gulf of Guinea to the New World from the 17th century onward
often were infected with guinea worms, particularly those from Ghana,
Gambia and Benin. Fortunately, dracunculiasis never became firmly established
in the Americas, although a few foci persisted for awhile in northern
South America.

Many
believe that the caduceus, the symbol of the medical profession, is
derived from the guinea worm rather than the snake, since in indigenous
areas the worm is still extracted from subcutaneous tissues by winding
it around a small stick, which is twisted slightly each day until the
entire worm is removed. Because it may be several feet in length, this
is sufficiently dramatic to impress its identity upon one's memory.

In 1947, Stoll estimated that over 48 million people in Africa, India,
Arabia, the Middle East and parts of Asia were infected with D. medinensis.
Later, Davey theorized that perhaps 50 million people in Africa alone
harbored the parasite. In the early 1980s, however, the World Health
Organization began a program to eradicate dracunculiasis as part of
the United Nations International Drinking Water Supply and Sanitation
Decade (1981-1990). So successful has this program been that, in February
1996, WHO reported that eradication had been 97% completed. The number
of cases worldwide had decreased from an estimated 3.5 million infected
individuals in 1986 to about 130,000 by the end of 1995, and the number
of endemic villages had decreased from over 23,000 in 1992 to less than
8,000 by the end of 1995. In most remaining endemic areas, the number
of infections had fallen to an average of 16 per village. A further
reduction in cases worldwide, to 70,000, was reported by WHO in 1998.

In
December 1995, an international evaluation of India's National Guinea
Worm Eradication Program concluded that transmission of the disease
had probably been completely interrupted there, and no further cases
were likely to occur. When the program began in 1983, dracunculiasis
was endemic in 12,840 villages in 89 districts of India, with about
40,000 infections and 13 million people at risk. By 1995, only 60 cases
were recorded in India, from 24 villages in 3 desert districts of Rajasthan.
This represents a remarkable reduction of over 99% since 1984 and is
a tribute to the tireless work, technology and funds supplied to India
and other countries by multiple national and international agencies
(including WHO, UNICEF, CDC and the Carter Center's Global 2000 Program)
in providing pure uncontaminated drinking water sources, adequate public
health education, and chemical vector control to impoverished villagers
in endemic areas.

Modern piping of pure water from fresh sources or filtration, boiling,
or chemical treatment of existing water supplies to kill infected cyclops
(the tiny intermediate hosts) markedly reduces exposure to guinea worm
infection. Thus, the Centers for Disease Control (CDC) reported that
the construction of a piped water facility for a Nigerian town of 30,000
reduced the incidence of guinea worm from over 60% to zero within 2
years.

The year 2000 is the target date for global eradication and at present
Pakistan, Iran and many other previously endemic countries have been
declared free of transmission. All significant remaining areas of infection
are in tropical Africa, where Sudan, reporting 50,000 cases in 1994,
presents special problems because of political unrest and strife there.
When global elimination is finally achieved, dracunculiasis will be
only the second disease eradicated in the history of mankind - - smallpox
in 1979 being the other.